Mars or AIDS?

I read somewhere that the
cost of going to Mars may eventually total up to $170 billion which is nowhere
close to the $12 billion the US President has stated will flow into NASA's
coffers over the next 5 years to help finance the Mars dream. I don't want to
knock the US government's spending on AIDS (supposedly $1
billion this year) but aren't there significant, higher priority problems
on Earth that need tackling before one starts dabbling in interplanterary conquest?